Our overall objective is to gain a molecular understanding of morphogenetic processes in higher organisms by examining the development of the embryonic limb. In this effort we are focussing on the process of chondrogenesis. We propose to study the synthesis of the protein backbone of proteochondroitin sulfate in an attempt to elucidate the regulatory steps involving this molecule at the time of chondrogenesis. We will further explore the possible role of the extracellular matrix in the maintenance of the cartilage phenotype. We will also study the fibrolo-genesis of cartilage collagen by analyzing the collagen of cartilage from other mutants.